Novel benzothiazyl disulfides, their preparation and use as lubricant additives

ABSTRACT

Preparation of novel 2-benzothiazyl disulfides by reacting sulfenyl chlorides with mercaptobenzothiazoles or ammonium or alkali metal salts thereof, and the use of the novel benzothiazyl disulfides as lubricant additives. In a specific embodiment, 1,1,3,3-tetramethylbutyl 2-benzothiazyl disulfide is produced by reacting 2,4,4-trimethyl-2-pentanesulfenyl chloride with at least one of 2-mercaptobenzothiazole and the ammonium and alkali metal salts thereof. In another specific embodiment, lubricants containing 1,1,3,3-tetramethylbutyl 2-benzothiazyl disulfide exhibit improved properties.

United States Patent Williams et al.

NOVEL BENZOTHIAZYL DISULFIDES, THEIR PREPARATION AND USE AS LUBRICANTADDITIVES Inventors: Ralph P. Williams; Rector P.

Louthan, both of Bartlesville, Okla.

Phillips Petroleum Company, Bartlesville, Okla.

Filed: May 17, 1973 Appl. No.: 361,242

Assignee:

References Cited UNITED STATES PATENTS 3/1955 Kopp et al. 252/3722,963,433 12/1960 Little et al. 252/47 X Primary ExaminerW. Cannon [57]ABSTRACT Preparation of novel 2-benzothiazyl disulfides by reactingsulfenyl chlorides with mercaptobenzothiazoles or ammonium or alkalimetal salts thereof, and the use of the novel benzothiazyl disulfides aslubricant additives. In a specific embodiment, l,l,3,3-tetramethylbutyl2-benzothiazyl disulfide is produced by reacting2,4,4-trimethyl-2-pentanesulfenyl chloride with at least one ofZ-mercaptobenzothiazole and the ammonium and alkali metal salts thereof.In another specific embodiment, lubricants containingl,l,3,3-tetramethylbutyl 2-benzothiazyl disulfide exhibit improvedproperties.

6 Claims, No Drawings NOVEL BENZOTHIAZYL DlISULFIDES, THEIR PREPARATIONAND USE AS LUBRICANT ADDITIVES BACKGROUND OF THE INVENTION Thisinvention relates to the production of novel benzothiazyl disulfides. Inaccordance with another aspect, this invention relates to the productionof benzothiazyl disulfides by reacting a sulfenyl chloride with at leastone of Z-mercaptobenzothiazole or ammonium or alkali metal saltsthereof. In accordance with another aspect, this invention relates tolubricants exhibiting improved properties containing at least one 2-benzothiazyl disulfide. In accordance with a further aspect, thisinvention relates to improved lubricants containing C -C benzothiazyldisulfides.

RELATED PRIOR ART Various organic compounds have, in the past, beenproposed and used as additives in lubricating oils. However, none ofthese compounds have been considered entirely adequate for the purposefor which they were intended because they did not suffieiently improvethe antiwear and extreme pressure lubricating properties of the oils,they did not improve the resistance to oxygen and they were oftencorrosive, especially to copper materials.

1 :Accordingly, an object of this invention is to provide novelcompounds.

It is another object of this invention to provide a process for theproduction of new compositions.

A further object of this invention is to provide novel compounds usefulas ashless lubricant additives.

It is another object of this invention to provide improved ashlesslubricant additives which exhibit superior characteristics when comparedwith former lubricant additives.

Another object of this invention is to provide improved lubricating oilsand greases.

A further object of this invention is to provide lubricating oils andgreases improved in high pressure or extreme pressure characteristics.

A further object of this invention is to provide lubricating oils andgreases having increased stability toward oxidation and rust.

Other objects and aspects as well as the several advantages of theinvention will be apparent to those skilled in the art upon reading thespecification and the appended claims.

In accordance with the invention, novel compounds are producedcomprising tert-alkyl Z-benzothiazyl disulfides having the formulan-c-silo about 5 to about 13, preferably about 7 to about 11.

In accordance with one embodiment, 1,l,3,3-tetramethylbutylZ-benzothiazyl disulfide, a mixture of isomeric tert-nonyl2-benzothiazy'l disulfides and isomeric tert-decyl 2-benzothiazyldisulfides, all novel compositions, are produced.

In accordance with a further embodiment, the above defined benzothiazyldisulfides are employed as ashless lubricant additives.

The compounds thus obtained are particularly useful as ashless lubricantadditives. Specifically, the oils and greases to which the instantcompounds are added exhibit improved resistance to oxidation andimproved anti-wear and extreme pressure lubricating properties.Furthermore, the disulfide additives of this invention are liquid orlow-melting solids, thus making easier their blending into oils andgreases. Further, the disulfide additives of this invention can beemployed in lubricants without a corrosion inhibitor and lubricantformulations containing these additives are noncorrosive to copper.

A particularly effective and presently preferred disulfide additive ofthis invention is 1,1 ,3,3-tetramethylbutyl 2-benzothiazyl disulfide.

Also in accordance with this invention, the novel tert-alkylZ-benzothiazyl disulfides as defined by the generic formula shown abovecan be produced by the reaction of a sulfenyl chloride having theformula R-C-S-Cl where each R is an unbranched or branched alkyl radicalhaving 1 to about 11 carbon atoms, preferably 1 to about 9 carbon atoms,the total number of carbon atoms in all of said R groups being withinthe range of about 5 to about 13, preferably about 7 to about 11, withat least one of 2-mercaptobenzothiazole or ammonium or alkali metal saltthereof.

The Z-mercaptobenzothiazole is preferably employed as an alkali metalsalt, i.e., as the lithium, sodium, potassium, rubidium, or cesium salt.The sodium salt of 2-mercaptobenzothiazole is the preferred alkali metalsalt. When 2-mercaptobenzothiazole is employed, it is preferable thatthere be used a base such as ammonium hydroxide or an alkali metalhydroxide, oxide, or carbonate at least sufficient to provide oneequivalent of base per mole of Z-mercaptobenzothiazole.

The mole ratio of 2-mercaptobenzothiazole or ammonium or alkali metalsalt thereof to sulfenyl chloride can vary considerably but generallywill be within the range of about 0.95:1 to about 1.2:1, preferablybeing about 1:1.

Although the reaction temperature can vary over a considerable range, itgenerally will be within the range of about 0C to about 150C, preferablyabout 20C to about C. The reaction time can vary considerably, dependingin part on the reaction temperature, but generally will be within therange of about 10 seconds to about 12 hours, preferably about 5 minutesto about 30 minutes.

In accordance with a preferred embodiment of the 2-mercaptobenzothiazoleor (b) the ammonium or alkali metal salts thereof.

The sulfenyl chloride should be dissolved in a saturated aliphatic orsaturated cycloaliphatic hydrocarbon having from 5 to about 16 carbonatoms per molecule and preferably 6 or 7 carbon atoms per molecule.Examples of such hydrocarbons include pentane, hexane, heptane,Z-methyloctane, dodecane, hexadccane, cyclopentane, cyclohexane,cycloheptane, methylcyclopentane, and the like, and mixtures thereof.Preferably, there is present a solvent such as water for the ammonium oralkali metal salt of the Z-mercaptobenzothiazole, regardless of whetherthe salt is employed as such or produced in situ.

The pressure for the reaction need be only sufficient to maintain thesolvent or solvents in the liquid phase.

The sulfenyl chloride used in this reaction can be prepared convenientlybe reacting the corresponding mercaptan or disulfide with chlorine orsulfuryl chloride by conventional procedures.

Examples of some sulfenyl chlorides which can be employed to produce thetert-alkyl 2-benzothiazyl-disulfides of this invention include2-methyl-2- pentanesulfenyl chloride, 3-methyl-3-hexanesulfenylchloride, 2,4,4-trimethyl-2-pentanesulfenyl chloride,2,3-dimethyl-3-octanesulfenyl chloride, 4-ethyl-8-methyl-4-nonanesulfenyl chloride, 2,4,6-trimethyl-4-ethylheptanesulfenyl chloride, 2,5,7,9-tetramethyl-2- decanesulfenylchloride, 2,3,3-trimethyl- 2-hexanesulfenyl chloride, 2,4,5-trimethyl-2-hexanesulfenyl chloride, 2,2,4-trimethyl-4- heptanesulfenyl chloride,and 2,2,3-trimethyl-3- heptanesulfenyl chloride, and the like, andmixtures thereof.

Examples of some tert-alkyl 2-benzothiazyl disulfides which can beproduced from the sulfenyl chlorides and Z-mercaptobenzothiazole orsalts thereof, and which can be employed as lubricant additives inaccordance with this invention, include 1,1-dimethylbutyl 2-benzothiazyl disulfide, l-methyl-l-ethylbutyl 2- benzothiazyl disulfide,l,l,3,3-tetramethylbutyl 2- benzothiazyl disulfide,1-methyl-l-isopropylhexyl 2- benzothiazyl disulfide,l-ethyl-l-propyl-5-methylhexyl 2-benzothiazyl disulfide, 1,1,3,5-tetramethyl-3- ethylhexyl 2-benzothiazyl disulfide, 1,1,4,6,8-pentamethylnonyl 2-benzothiazyl disulfide, l ,1,2,2-tetramethylpentyl Z-behzothiazyl disulfide,l,l,3,4-tetramethylpentyl 2-benzothiazyl disulfide,1,3,3-trimethyl-lpropylbutyl 2-benzothiazyl disulfide, andl-methyl-ltert-butylpentyl 2-benzothiazyl disulfide, and the like, andmixtures thereof.

In the preparation of the lubricating compositions containing theinstant 2-benzothiazyl disulfides, various mineral oils are employed.Generally, these are of petroleum origin and are complex mixtures ofmany hydrocarbon compounds. Preferably, the mineral oils are refinedproducts such as are obtained by well-known refining processes, such asby hydrogenation, polymerization, dewaxing, etc. Frequently, the oilshave a Saybolt viscosity at 100F in the range from about 60 to 5,000 anda Saybolt viscosity at 210F of about 30 to 250. The oils can be of theparaffinic, naphthenic, or aromatic types, as well as mixtures of one ormore types. The additives of the invention have special advantages whenemployed with paraffinic types of oils such as are obtained by solventextraction of a suitable refinery stream. Many suitable lubricatingcompositions are available as commercial products such as those used asmotor oils, fuel oils, gear oils, automatic transmission oils, and thelike.

Generally, any conventional and commercially available grease can beused in accordance with this invention. The grease employed can havebeen thickened in any known manner such as by the use of soaps and/or bydissolving polymers in the oil at temperatures of at least 245F and thelike.

Suitable greases include substantially any grade of flowable grease asdefined by the National Lubricating Grease Institute (NLGl). Forexample, NLGl grade greases from 000 to 6 can be employed in thisinvention. Also, greases having an ASTM D 217-68 penetration' at 60strokes in the range of to 475 can be employed.

The lubricating oil bases which can be employed to make grease of thisinvention can be mineral, vegetable, or animal in nature, preferablylubricant bases having at least a major amount of mineral origin. Suchoils include refined oils having a viscosity of from about 35 to about240 SUS at 210F. White mineral oil as well as other specialty oils canbe used and are among the preferred oils.

The amount of tert-alkyl 2-benzothiazyl disulfide, as defined above,which is incorporated into the lubricants according to the invention canrange from about 0.05 in weight percent to about 10 weight percent,preferably about 0.1 weight percent to about 5 weight percent and mostdesirably about 0.2 weight percent to about 2 weight percent, based onthe total weight of the composition, i.e., the total weight oflubricant, including any other additives which may be present, plus thetert-alkyl 2-benzothiazyl disulfide.

Thickeners for the oils can be employed in amounts up to 20 weightpercent of the oil. Various soaps normally used to thicken greases canbe used, and they include metal salts of high molecular weight acids,for example, acids of 10 to 30 carbon atoms, and preferably 16 to 24carbon atoms, either synthetic or of animal or vegetable origin. Othercarboxylic acids useful for making soaps of metal salts include thosederived from tallows, hydrogenated fish oil, castor oil, wool grease,and rosin. Generally, the alkali metal or alkaline earth metal oraluminum or lead salts of acids such as lauric, palmitic, oleic,stearic, and the like are used. One of the preferred soaps is thelithium soap of 12-hydroxystearic acid. While soaps of a general naturecan be used in the greases of this invention, it should be understoodthat the invention includes use with soapless greases formedessentiallyfrom polymers and oil alone, with or without small amounts of knowngrease additives such as fillers and the like. Thus, polymers such aspolyethylene and polypropylene can be employed as thickeners, together,alone or in conjunction with other thickeners such as soap.

Other materials normally used in greases can also be employed in thegreases applicable to this invention. For example, additives such asrust inhibitors, antioxidants, fillers, pigments, perfumes, and the likecan be employed. Some examples of such materials includepropylenediamine, phenyl-a-naphthylamine, phenothiazine, mica, asbestos,powdered lead, powdered zinc, talc, alumina, titanium dioxide,molybdenum disulfide, bentones, carbon black, nitrobenzene, and thelike. Generally, the amount of these modifiers is less than about 10percent of the total weight of the grease.

Other agents than those which have been mentioned can be present in thelubricant composition such as dyes, pour point depressants, heatthickened fatty oils, sulfurized fatty oils, sludge dispersers, foamsuppressants, thickeners, viscosity index improvers, oiliness.

agents, resins, rubber, molten polymers, and the like.

SPECIFIC EXAMPLES EXAMPLE I To a stirred solution of 146 g (1.0 mole) of2,4,4- trimethyl-2-pentanethiol and 800 ml of heptane in a 3- liter,3-necked flask equipped with stirrer, reflux condenser, and droppingfunnel was added 135 g (1.0 mole) of sulfuryl chloride over a period ofabout minutes. There was a vigorous evolution of gas during theaddition. The reaction solution was heated to reflux (about 95C) toremove the remaining hydrogen chloride and sulfur dioxide and thencooled to about 50C.

To the resulting mixture, comprising 2,4,4-trimethyl- Z-pentanesulfenylchloride, was added rapidly an aqueous solution prepared from 400 mlwater, 44 g (1.1 moles) sodium hydroxide, and 167 g (1.0 mole)2mercaptobenzothiazole. The two phases thus formed were stirred togetherfor about 20 minutes, after which the phases were separated, and the oilphase was washed twice with water (500 ml portions). The solvent wasstripped from the oil phase by heating at about 1 mm Hg pressure in asteam bath to obtain 264.2 g (87.8 percent yield) of1,1,3,3-tetramethylbutyl 2- benzothiazyl disulfide as a residualslightly viscous, reddish brown liquid which was subjected to elementalanalysis. Analysis, weight percent: Calculated for C H ,NS C, 57.8; H,6.8; N, 4.5; S, 30.9. Found: C, 58.4; H, 7.7; N, 4.2; S, 31.2.

EXAMPLE II A mixture comprising isomeric tert-nonylsulfenyl chloridesand isomeric tert-decylsulfenyl chlorides was prepared by reaction ofchlorine with a mercaptan mixture comprising about 62 weight percentisomeric tertnonyl mercaptans, about 36 weight percent isomerictert-decyl mercaptans, and about-2 weight percent olefins. Analysis ofthis mercaptan mixture showed it had the following properties:

Mercaptan Sulfur, weight percent 19.14 Average Molecular Weight, Basedon Mercaptan Sulfur Content 167 Specific Gravity, 60/60 F 0.8531

API Gravity 34.4

Flash Point, TOC, F 148 5 mm Hg Distillation, F

To prepare the sulfenyl chlorides, 278.6 g (1.67 moles, based onmercaptan sulfur content) of the above mercaptan mixture was dissolvedin sufficient heptane to give 1500 ml of solution. The major portion ofthis solution (1350 ml, containing 15 moles of mercaptans) was passedthrough a glass mixing tee where it was contacted with a stream ofchlorine (107 g, 1.5

moles) in approximately a stoichiometric ratio over a period of one andone-half hours. The resulting mixture comprising isomerictert-nonylsulfenyl chlorides and isomeric tert-decylsulfenyl chloridesin heptane was then stirred with a solution prepared from 300 ml water,66.0 g (1.65 moles) sodium hydroxide, and 250.5 g 1.5 moles)2-mercaptobenzothiazole for 30 minutes on a steam bath. The organic andaqueous phases were separated, and the organic phase was washed twicewith water and then filtered, after which heptane was distilled underreduced pressure on a steam bath. The residual liquid product, whichweighed 449.0 g, consisted essentially of a mixture of isomerictert-nonyl 2- benzothiazyl disulfides and isomeric tert-decyl 2-benzothiazyl disulfides, this mixture of disulfides being referred tohere and in subsequent Examples as C 13D. Elemental analysis of this CBD showed it contained 59.9 weight percent carbon, 7.7 weight percenthydrogen, 4.1 weight percent nitrogen, and 27.2 weight percent sulfur.

EXAMPLE III l,l,3,3-tetramethylbutyl 2-benzothiazyl disulfide (C BD) andC BD (described in Example 11) were evaluated as extreme pressurelubricant additives in the Timken O.K. load test (ASTM D 2509-68), usinga commercial lithium base grease, Grade 2. For comparative purposes, thetest was also conducted on the same grease with no extreme pressurelubricant additive, as well as on the same grease containing tert-butyl2- benzothiazyl disulfide (C BD), a known extreme pressure lubricantadditive. The results are shown in Table I. In this example, as in theexamples which follow, the weight percent additive is based on the totalweight of lubricant plus additive.

TABLE I Additive Timken O.K.Load, Lb.

None 10 C BD, 1 wt. 3O C BD, 2 wt. 45 C,,BD, 3 wt. 50 C BD, 2 wt. 70 50C BD, 2 wt. 40

Table I shows that C BD and C BD were effective as extreme pressurelubricant additives, and that at a comparable concentration they weresuperior to C BD.

EXAMPLE IV TABLE II Additive Number of Teeth Wear Concentration C ,BD C,BD -C,, ,BD

lWtf/z 24&25 33&35 23&27

Table II shows that in the Falex testthe antiwear properties of CgBD andQ BD were substantially better than those of C BD.

EXAMPLE V The antiwear properties of l,l,3,3-tetramethylbutyl2-benzothiazyl disulfide (C BD) and tert-butyl 2- benzothiazyl disulfide(C BD), each at a concentration (C BD) was evaluated as an antiwearadditive in a fully compounded SAE lW-40 API Service SE motor oilwithout antiwear agent. The evaluation was a Sequence I type valve trainwear test conducted in accordance with ASTM Special TechnicalPublication No. 3 l5-A,

Engine Test Sequences for Evaluating Automotive Lubricants for APIService MS, American Society for Testing and Materials, Philadelphia,Pennsylvania (September 1963), except that a 1967 Oldsmobile engine wasused instead ofa 1960 Oldsmobile engine. For comparative purposes,control tests were conducted using the same motor oil (1) withoutantiwear agent and (2) with Lubrizol 1395 (zinc dialkyldithiophosphate), a widely used antiwear additive. The results of thesetests are shown in Table V.

'of 1 weight percent, were compared in the 4-ball wear test (ASTM D2596-69), using the ashless crankcase motor oil described in Example IV.The results are shown in Table III.

TABLE III Load, kg Wear, microns C BD C BD 100 1959 1920 120 2061 2019140 2349 2155 160 2937 2706 180 3030 2781 200 Welded Welded The resultsin Table III indicate that, within experimental error, in the 4-ballwear test the antiwear properties of CgBD and C BD were substantiallyequivalent.

EXAMPLE VI TABLE IV Additive Concentration Minutes to -lb. Pressure DropC BD 1 weight percent 28 The higher value shown in Table IV for C BDthan for C BD indicates the formulation containing C BD was slightlymore stable to oxidation than was the formulation containing C BD.

EXAMPLE VII 2-benzothiazyl disulfide 1,1,3,3-tetramethylbutyl Table Vshows that use of the ashless lubricant additive C BD at each of theconcentration levels employed provided some protection against wear. Atthe concentration of 0.2 weight percent, C BD afforded wear protectionapproximately comparable to that provided by Lubrizol 1395, which is notashless, at a concentration of 0.19 weight percent.

As will be evident to those skilled in the art, there are variations andmodifications of this invention which can be practiced in view of theforegoing disclosure without departing from the spirit and scope of theinvention.

We claim:

1. An improved lubricating composition comprising major amounts of amineral lubricating oil having incorporated herein a small minor amountof a tert-alkyl 2-benzothiazyl disulfide selected from the groupconsisting of l, l, 3, 3-tetramethylbutyl 2-benzothiazyl disulfide and amixture of isomeric tert-nonyl 2- benzothiazyl disulfides and isomerictert-decyl 2- benzothiazyl disulfides sufficient to improve at least oneof the properties of the resulting lubricating composition, saidproperties including antiwear and extreme pressure characteristics andstability toward oxidation and rust.

2. A composition according to claim 1 wherein the quantity of tert-alkylZ-benzothiazyl disulfide ranges from 0.05 to about 10 weight percent.

3. A composition according to claim 1 wherein said mineral lubricatingoil has been thickened with an alkali metal soap to form a greaseformulation.

4. A composition according to claim 1 wherein the tert-alkyl2-benzothiazyl disulfide is l,l,3,3-tetramethylbutyl Z-benzothiazyldisulfide.

5. A composition according to claim 1 wherein the tert-alkyl2-benzothiazyl disulfide is a mixture of isomeric tert-nonyl2-benzothiazyl disulfides and isomeric tert-decyl 2-benzothiazyldisulfides.

6. A composition according to claim 1 wherein the amount of tert-alkyl2-benzothiazyl disulfide present ranges from about 0.1 to about 5 weightpercent.

1. AN IMPROVED LUBRICATING COMPOSITION COMPRISING MAJOR AMOUNTS OF AMINERAL LUBRICATING OIL HAVING INCORPORATED HEREIN A SMALL MINOR AMOUNTOF A TERT-ALKYL 2-BENZOTHIAZYL DISULFIDE SELECTED FROM THE GROUPCONSISTING OF 1, 1, 3, 3TETRAMETHYLBUTYL 2-BENZOTHIAZYL DISULFIDE AND AMIXTURE OF ISOMERIC TERT-NONYL 2-BENZOTHIAZYL DISULFIDES AND ISOMERICTERT-DECYL 2-BENZOTHIAZYL DISULFIDES SUFFICIENT TO IMPROVE AT LEAST ONEOF THE PROPERTIES OF THE RESULTING LUBRICATING COMPOSITION, SAIDPROPERTIES INCLUDING ANTIWEAR AND EXTREME PRESSURE CHARACTERISTICS ANDSTABILITY TOWARD OXIDATION AND RUST.
 2. A composition according to claim1 wherein the quantity of tert-alkyl 2-benzothiazyl disulfide rangesfrom 0.05 to about 10 weight percent.
 3. A composition according toclaim 1 wherein said mineral lubricating oil has been thickened with analkali metal soap to form a grease formulation.
 4. A compositionaccording to claim 1 wherein the tert-alkyl 2-benzothiazyl disulfide is1,1,3,3-tetramethylbutyl 2-benzothiazyl disulfide.
 5. A compositionaccording to claim 1 wherein the tert-alkyl 2-benzothiazyl disulfide isa mixture of isomeric tert-nonyl 2-benzothiazyl disulfides and isomerictert-decyl 2-benzothiazyl disulfides.
 6. A composition according toclaim 1 wherein the amount of tert-alkyl 2-benzothiazyl disulfidepresent ranges from about 0.1 to about 5 weight percent.